822 



THE NATIONAL GEOGRAPHIC MAGAZINE 



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INSIDE THE SPIDER THERE S FOOD BUT NO PRIVACY 



During fall and winter, Smithi's slow growtii can easily be observed, 

 because of its wiiiteness and the transparency of the host's abdominal skin 

 (upper picture). "Twins" and "triplets" and, ver\- rarely, "quadruplets" 

 are found in an occasional spider, and in these cases the adult flies are 

 dwarfed. The predatory larva's appetite improves with the coming of 

 spring, until she is so fat she seems almost to fill the spider's body. Yet 

 the unwilling host is still alive and kicking ! Passing quickly through a 

 scalloped, segmented phase (lower), the unwelcome boarder, by mid-July, 

 is readv to take leave of her long-suffering "meal ticket." 



last, her slender -waist torn apart by her 

 forty-first opponent. 



And so, bit by bit, these fascinating wasps 

 revealed their life secrets behind the ob- 

 servation windows of my cages. Many 

 times I saw Psammy lay her egg upon the 

 abdomen of a paralyzed spider (page 814). 

 T saw the egg hatch, and the young larva 

 begin to feed upon the unspoiled spider 

 meat so marvelously preserved for its use 

 (pages 815 and 816). 



I have known a spi- 

 der to live for more 

 than six months in 

 this paralyzed state of 

 partially suspended 

 animation— Psammy 's 

 perfect process of 

 cold storage without 

 refrigeration ! 



To me, the wonder 

 of it is that this is 

 not the ferocity of a 

 meat-eating animal, 

 for Psammy herself 

 lives upon the nectar 

 of flowers. She kills 

 only to provide food 

 for her babies-to-be. 



And then I watched 

 in amazement as the 

 mature larva spun a 

 marvelous cocoon 

 with its mouth. How 

 could this mere skin- 

 ful of digested spider 

 meat have the myste- 

 rious intelligence that 

 enabled it to outspin 

 even the trapdoor 

 spider, in building its 

 complicated, two- 

 story cocoon? 



INTO THE killer's 

 HIDE-OUT 



Then the Psammy 

 larva spun itself out 

 of sight in its cocoon, 

 and I was up against 

 my old, old disap- 

 pointment — when the 

 butterfly larvae had 

 hidden within their 

 mummy-case chrysa- 

 lids. But this time 

 I kept right on the 

 heels of my quarry 

 and followed Psammy into her hide-out. 

 The butterfly chrysalis is attached to, 

 and a part of, the pupa within, but T knew 

 that the wasp larva was not attached to the 

 cocoon and did not fill it completely. So, 

 very carefully, I cut away one side of the 

 stiff cocoon and fitted it snugly behind an 

 observation window, just as I had fixed the 

 trapdoor nest. 



And so at last, after many years, T could 

 see and stud}' "what happened inside," and 



